NAME

SYNOPSIS

to list some (not all may be available simultaneously), or it may
be read as is: either as README.os2, or pod/perlos2.pod.

To read the .INF version of documentation (very recommended)
outside of OS/2, one needs an IBM's reader (may be available on IBM
ftp sites (?) (URL anyone?)) or shipped with PC DOS 7.0 and IBM's
Visual Age C++ 3.5.

A copy of a Win* viewer is contained in the "Just add OS/2 Warp" package

ftp://ftp.software.ibm.com/ps/products/os2/tools/jaow/jaow.zip

in ?:\JUST_ADD\view.exe. This gives one an access to EMX's
.INF docs as well (text form is available in /emx/doc in
EMX's distribution). There is also a different viewer named xview.

Note that if you have lynx.exe or netscape.exe installed, you can follow WWW links
from this document in .INF format. If you have EMX docs installed
correctly, you can follow library links (you need to have viewemxbook
working by setting EMXBOOK
environment variable as it is described
in EMX docs).

DESCRIPTION

Target

The target is to make OS/2 one of the best supported platform for
using/building/developing Perl and Perl applications, as well as
make Perl the best language to use under OS/2. The secondary target is
to try to make this work under DOS and Win* as well (but not too hard).

The current state is quite close to this target. Known limitations:

Some *nix programs use fork() a lot; with the mostly useful flavors of
perl for OS/2 (there are several built simultaneously) this is
supported; but some flavors do not support this (e.g., when Perl is
called from inside REXX). Using fork() after
useing dynamically loading extensions would not work with very old
versions of EMX.

You need a separate perl executable perl__.exe (see perl__.exe)
if you want to use PM code in your application (as Perl/Tk or OpenGL
Perl modules do) without having a text-mode window present.

While using the standard perl.exe from a text-mode window is possible
too, I have seen cases when this causes degradation of the system stability.
Using perl__.exe avoids such a degradation.

There is no simple way to access WPS objects. The only way I know
is via OS2::REXX
and SOM
extensions (see OS2::REXX, Som).
However, we do not have access to
convenience methods of Object-REXX. (Is it possible at all? I know
of no Object-REXX API.) The SOM
extension (currently in alpha-text)
may eventually remove this shortcoming; however, due to the fact that
DII is not supported by the SOM
module, using SOM
is not as
convenient as one would like it.

Please keep this list up-to-date by informing me about other items.

Other OSes

Since OS/2 port of perl uses a remarkable EMX environment, it can
run (and build extensions, and - possibly - be built itself) under any
environment which can run EMX. The current list is DOS,
DOS-inside-OS/2, Win0.3*, Win0.95 and WinNT. Out of many perl flavors,
only one works, see perl_.exe.

Note that not all features of Perl are available under these
environments. This depends on the features the extender - most
probably RSX - decided to implement.

Prerequisites

EMX

EMX runtime is required (may be substituted by RSX). Note that
it is possible to make perl_.exe to run under DOS without any
external support by binding emx.exe/rsx.exe to it, see emxbind. Note
that under DOS for best results one should use RSX runtime, which
has much more functions working (like fork, popen
and so on). In
fact RSX is required if there is no VCPI present. Note the
RSX requires DPMI. Many implementations of DPMI are known to be very
buggy, beware!

Only the latest runtime is supported, currently 0.9d fix 03. Perl may run
under earlier versions of EMX, but this is not tested.

One can get different parts of EMX from, say

ftp://crydee.sai.msu.ru/pub/comp/os/os2/leo/gnu/emx+gcc/

http://hobbes.nmsu.edu/h-browse.php?dir=/pub/os2/dev/emx/v0.9d/

The runtime component should have the name emxrt.zip.

NOTE. When using emx.exe/rsx.exe, it is enough to have them on your path. One
does not need to specify them explicitly (though this

emxperl_.exe -de0

will work as well.)

RSX

To run Perl on DPMI platforms one needs RSX runtime. This is
needed under DOS-inside-OS/2, Win0.3*, Win0.95 and WinNT (see
Other OSes). RSX would not work with VCPI
only, as EMX would, it requires DMPI.

Having RSX and the latest sh.exe one gets a fully functional
*nix-ish environment under DOS, say, fork, ``
and
pipe-open work. In fact, MakeMaker works (for static build), so one
can have Perl development environment under DOS.

One can get RSX from, say

http://cd.textfiles.com/hobbesos29804/disk1/EMX09C/

ftp://crydee.sai.msu.ru/pub/comp/os/os2/leo/gnu/emx+gcc/contrib/

Contact the author on rainer@mathematik.uni-bielefeld.de
.

The latest sh.exe with DOS hooks is available in

http://www.ilyaz.org/software/os2/

as sh_dos.zip or under similar names starting with sh
, pdksh
etc.

HPFS

Perl does not care about file systems, but the perl library contains
many files with long names, so to install it intact one needs a file
system which supports long file names.

Note that if you do not plan to build the perl itself, it may be
possible to fool EMX to truncate file names. This is not supported,
read EMX docs to see how to do it.

pdksh

To start external programs with complicated command lines (like with
pipes in between, and/or quoting of arguments), Perl uses an external
shell. With EMX port such shell should be named sh.exe, and located
either in the wired-in-during-compile locations (usually F:/bin),
or in configurable location (see PERL_SH_DIR).

For best results use EMX pdksh. The standard binary (5.2.14 or later) runs
under DOS (with RSX) as well, see

http://www.ilyaz.org/software/os2/

Starting Perl programs under OS/2 (and DOS and...)

Start your Perl program foo.pl with arguments arg1arg2arg3
the
same way as on any other platform, by

perlfoo.plarg1arg2arg3

If you want to specify perl options -my_opts
to the perl itself (as
opposed to your program), use

perl -my_optsfoo.plarg1arg2arg3

Alternately, if you use OS/2-ish shell, like CMD or 4os2, put
the following at the start of your perl script:

extprocperl -S -my_opts

rename your program to foo.cmd, and start it by typing

fooarg1arg2arg3

Note that because of stupid OS/2 limitations the full path of the perl
script is not available when you use extproc
, thus you are forced to
use -S
perl switch, and your script should be on the PATH
. As a plus
side, if you know a full path to your script, you may still start it
with

To understand what the above magic does, read perl docs about -S
switch - see perlrun, and cmdref about extproc
:

viewperlperlrun

manperlrun

viewcmdrefextproc

helpextproc

or whatever method you prefer.

There are also endless possibilities to use executable extensions of
4os2, associations of WPS and so on... However, if you use
*nixish shell (like sh.exe supplied in the binary distribution),
you need to follow the syntax specified in Switches in perlrun.

For the sake of speed for a common case, in the above algorithms
backslashes in the command name are not considered as shell metacharacters.

Perl starts scripts which begin with cookies
extproc
or #!
directly, without an intervention of shell. Perl uses the
same algorithm to find the executable as pdksh: if the path
on #!
line does not work, and contains /, then the directory
part of the executable is ignored, and the executable
is searched in . and on PATH
. To find arguments for these scripts
Perl uses a different algorithm than pdksh: up to 3 arguments are
recognized, and trailing whitespace is stripped.

If a script
does not contain such a cooky, then to avoid calling sh.exe, Perl uses
the same algorithm as pdksh: if $ENV{EXECSHELL}
is set, the
script is given as the first argument to this command, if not set, then
$ENV{COMSPEC} /c
is used (or a hardwired guess if $ENV{COMSPEC}
is
not set).

When starting scripts directly, Perl uses exactly the same algorithm as for
the search of script given by -S command-line option: it will look in
the current directory, then on components of $ENV{PATH}
using the
following order of appended extensions: no extension, .cmd, .btm,
.bat, .pl.

Note that Perl will start to look for scripts only if OS/2 cannot start the
specified application, thus system'blah'
will not look for a script if
there is an executable file blah.exeanywhere on PATH
. In
other words, PATH
is essentially searched twice: once by the OS for
an executable, then by Perl for scripts.

Note also that executable files on OS/2 can have an arbitrary extension,
but .exe will be automatically appended if no dot is present in the name.
The workaround is as simple as that: since blah. and blah denote the
same file (at list on FAT and HPFS file systems), to start an executable residing in file n:/bin/blah (no
extension) give an argument n:/bin/blah. (dot appended) to system().

Perl will start PM programs from VIO (=text-mode) Perl process in a
separate PM session;
the opposite is not true: when you start a non-PM program from a PM
Perl process, Perl would not run it in a separate session. If a separate
session is desired, either ensure
that shell will be used, as in system'cmd /c myprog'
, or start it using
optional arguments to system() documented in OS2::Process
module. This
is considered to be a feature.

Frequently asked questions

"It does not work"

Perl binary distributions come with a testperl.cmd script which tries
to detect common problems with misconfigured installations. There is a
pretty large chance it will discover which step of the installation you
managed to goof. ;-)

I cannot run external programs

Do you try to run internal shell commands, like `copy a b`
(internal for cmd.exe), or `glob a*b`
(internal for ksh)? You
need to specify your shell explicitly, like `cmd /c copy a b`
,
since Perl cannot deduce which commands are internal to your shell.

I cannot embed perl into my program, or use perl.dll from my
program.

Is your program EMX-compiled with -Zmt -Zcrtdll
?

Well, nowadays Perl DLL should be usable from a differently compiled
program too... If you can run Perl code from REXX scripts (see
OS2::REXX), then there are some other aspect of interaction which
are overlooked by the current hackish code to support
differently-compiled principal programs.

If everything else fails, you need to build a stand-alone DLL for
perl. Contact me, I did it once. Sockets would not work, as a lot of
other stuff.

Some time ago I had reports it does not work. Nowadays it is checked
in the Perl test suite, so grep ./t subdirectory of the build tree
(as well as *.t files in the ./lib subdirectory) to find how it
should be done "correctly".

Cannot start find.exe "pattern" file

The whole idea of the "standard C API to start applications" is that
the forms foo
and "foo"
of program arguments are completely
interchangeable. find breaks this paradigm;

find "pattern" file

find pattern file

are not equivalent; find cannot be started directly using the above
API. One needs a way to surround the doublequotes in some other
quoting construction, necessarily having an extra non-Unixish shell in
between.

This would start find.exe via cmd.exe via sh.exe
via
perl.exe
, but this is a price to pay if you want to use
non-conforming program.

INSTALLATION

Automatic binary installation

The most convenient way of installing a binary distribution of perl is via perl installer
install.exe. Just follow the instructions, and 99% of the
installation blues would go away.

Note however, that you need to have unzip.exe on your path, and
EMX environment running. The latter means that if you just
installed EMX, and made all the needed changes to Config.sys,
you may need to reboot in between. Check EMX runtime by running

emxrev

Binary installer also creates a folder on your desktop with some useful
objects. If you need to change some aspects of the work of the binary
installer, feel free to edit the file Perl.pkg. This may be useful
e.g., if you need to run the installer many times and do not want to
make many interactive changes in the GUI.

Things not taken care of by automatic binary installation:

PERL_BADLANG

may be needed if you change your codepage after perl installation,
and the new value is not supported by EMX. See PERL_BADLANG.

This file resides somewhere deep in the location you installed your
perl library, find it out by

perl -MConfig -le "print $INC{'Config.pm'}"

While most important values in this file are updated by the binary
installer, some of them may need to be hand-edited. I know no such
data, please keep me informed if you find one. Moreover, manual
changes to the installed version may need to be accompanied by an edit
of this file.

NOTE. Because of a typo the binary installer of 5.00305
would install a variable PERL_SHPATH
into Config.sys. Please
remove this variable and put PERL_SH_DIR instead.

Manual binary installation

As of version 5.00305, OS/2 perl binary distribution comes split
into 11 components. Unfortunately, to enable configurable binary
installation, the file paths in the zip files are not absolute, but
relative to some directory.

Note that the extraction with the stored paths is still necessary
(default with unzip, specify -d
to pkunzip). However, you
need to know where to extract the files. You need also to manually
change entries in Config.sys to reflect where did you put the
files. Note that if you have some primitive unzipper (like
pkunzip
), you may get a lot of warnings/errors during
unzipping. Upgrade to (w)unzip.

Below is the sample of what to do to reproduce the configuration on my
machine. In VIEW.EXE you can press Ctrl-Insert
now, and
cut-and-paste from the resulting file - created in the directory you
started VIEW.EXE from.

For each component, we mention environment variables related to each
installation directory. Either choose directories to match your
values of the variables, or create/append-to variables to take into
account the directories.

Perl VIO and PM executables (dynamically linked)

unzip perl_exc.zip *.exe *.ico -d f:/emx.add/bin

unzip perl_exc.zip *.dll -d f:/emx.add/dll

(have the directories with *.exe on PATH, and *.dll on
LIBPATH);

Perl_ VIO executable (statically linked)

unzip perl_aou.zip -d f:/emx.add/bin

(have the directory on PATH);

Executables for Perl utilities

unzip perl_utl.zip -d f:/emx.add/bin

(have the directory on PATH);

Main Perl library

unzip perl_mlb.zip -d f:/perllib/lib

If this directory is exactly the same as the prefix which was compiled
into perl.exe, you do not need to change
anything. However, for perl to find the library if you use a different
path, you need to
setPERLLIB_PREFIX
in Config.sys, see PERLLIB_PREFIX.

Additional Perl modules

unzipperl_ste.zip -d f:/perllib/lib/site_perl/5.14.0/

Same remark as above applies. Additionally, if this directory is not
one of directories on @INC (and @INC is influenced by PERLLIB_PREFIX
), you
need to put this
directory and subdirectory ./os2 in PERLLIB
or PERL5LIB
variable. Do not use PERL5LIB
unless you have it set already. See
ENVIRONMENT in perl.

[Check whether this extraction directory is still applicable with
the new directory structure layout!]

Tools to compile Perl modules

unzip perl_blb.zip -d f:/perllib/lib

Same remark as for perl_ste.zip.

Manpages for Perl and utilities

unzip perl_man.zip -d f:/perllib/man

This directory should better be on MANPATH
. You need to have a
working man to access these files.

Manpages for Perl modules

unzip perl_mam.zip -d f:/perllib/man

This directory should better be on MANPATH
. You need to have a
working man to access these files.

Source for Perl documentation

unzip perl_pod.zip -d f:/perllib/lib

This is used by the perldoc
program (see perldoc), and may be used to
generate HTML documentation usable by WWW browsers, and
documentation in zillions of other formats: info
, LaTeX
,
Acrobat
, FrameMaker
and so on. [Use programs such as
pod2latex etc.]

Perl manual in .INF format

unzip perl_inf.zip -d d:/os2/book

This directory should better be on BOOKSHELF
.

Pdksh

unzip perl_sh.zip -d f:/bin

This is used by perl to run external commands which explicitly
require shell, like the commands using redirection and shell
metacharacters. It is also used instead of explicit /bin/sh.

Set PERL_SH_DIR
(see PERL_SH_DIR) if you move sh.exe from
the above location.

Note. It may be possible to use some other sh-compatible shell (untested).

After you installed the components you needed and updated the
Config.sys correspondingly, you need to hand-edit
Config.pm. This file resides somewhere deep in the location you
installed your perl library, find it out by

perl -MConfig -le "print $INC{'Config.pm'}"

You need to correct all the entries which look like file paths (they
currently start with f:/).

Warning

The automatic and manual perl installation leave precompiled paths
inside perl executables. While these paths are overwriteable (see
PERLLIB_PREFIX, PERL_SH_DIR), some people may prefer
binary editing of paths inside the executables/DLLs.

Accessing documentation

Depending on how you built/installed perl you may have (otherwise
identical) Perl documentation in the following formats:

OS/2 .INF file

Most probably the most convenient form. Under OS/2 view it as

viewperl

viewperlperlfunc

viewperlless

viewperlExtUtils::MakeMaker

(currently the last two may hit a wrong location, but this may improve
soon). Under Win* see SYNOPSIS.

If you want to build the docs yourself, and have OS/2 toolkit, run

pod2ipf > perl.ipf

in /perllib/lib/pod directory, then

ipfc /infperl.ipf

(Expect a lot of errors during the both steps.) Now move it on your
BOOKSHELF path.

Plain text

If you have perl documentation in the source form, perl utilities
installed, and GNU groff installed, you may use

perldocperlfunc

perldocless

perldocExtUtils::MakeMaker

to access the perl documentation in the text form (note that you may get
better results using perl manpages).

Alternately, try running pod2text on .pod files.

Manpages

If you have man installed on your system, and you installed perl
manpages, use something like this:

man perlfunc

man 3 less

man ExtUtils.MakeMaker

to access documentation for different components of Perl. Start with

manperl

Note that dot (.) is used as a package separator for documentation
for packages, and as usual, sometimes you need to give the section - 3
above - to avoid shadowing by the less(1) manpage.

Make sure that the directory above the directory with manpages is
on our MANPATH
, like this

set MANPATH=c:/man;f:/perllib/man

for Perl manpages in f:/perllib/man/man1/ etc.

HTML

If you have some WWW browser available, installed the Perl
documentation in the source form, and Perl utilities, you can build
HTML docs. Cd to directory with .pod files, and do like this

cd f:/perllib/lib/pod

pod2html

After this you can direct your browser the file perl.html in this
directory, and go ahead with reading docs, like this:

explore file:///f:/perllib/lib/pod/perl.html

Alternatively you may be able to get these docs prebuilt from CPAN.

GNU info
files

Users of Emacs would appreciate it very much, especially with
CPerl
mode loaded. You need to get latest pod2texi
from CPAN
,
or, alternately, the prebuilt info pages.

PDF files

for Acrobat
are available on CPAN (may be for slightly older version of
perl).

LaTeX
docs

can be constructed using pod2latex
.

BUILD

Here we discuss how to build Perl under OS/2.

The short story

Assume that you are a seasoned porter, so are sure that all the necessary
tools are already present on your system, and you know how to get the Perl
source distribution. Untar it, change to the extract directory, and

gnupatch -p0 < os2\diff.configure

sh Configure -des -D prefix=f:/perllib

make

make test

make install

make aout_test

make aout_install

This puts the executables in f:/perllib/bin. Manually move them to the
PATH
, manually move the built perl*.dll to LIBPATH
(here for
Perl DLL * is a not-very-meaningful hex checksum), and run

make installcmd INSTALLCMDDIR=d:/ir/on/path

Assuming that the man
-files were put on an appropriate location,
this completes the installation of minimal Perl system. (The binary
distribution contains also a lot of additional modules, and the
documentation in INF format.)

What follows is a detailed guide through these steps.

Prerequisites

You need to have the latest EMX development environment, the full
GNU tool suite (gawk renamed to awk, and GNU find.exe
earlier on path than the OS/2 find.exe, same with sort.exe, to
check use

find --version

sort --version

). You need the latest version of pdksh installed as sh.exe.

Check that you have BSD libraries and headers installed, and -
optionally - Berkeley DB headers and libraries, and crypt.

Possible locations to get the files:

ftp://ftp.uni-heidelberg.de/pub/os2/unix/

http://hobbes.nmsu.edu/h-browse.php?dir=/pub/os2

http://cd.textfiles.com/hobbesos29804/disk1/DEV32/

http://cd.textfiles.com/hobbesos29804/disk1/EMX09C/

It is reported that the following archives contain enough utils to
build perl: gnufutil.zip, gnusutil.zip, gnututil.zip, gnused.zip,
gnupatch.zip, gnuawk.zip, gnumake.zip, gnugrep.zip, bsddev.zip and
ksh527rt.zip (or a later version). Note that all these utilities are
known to be available from LEO:

ftp://crydee.sai.msu.ru/pub/comp/os/os2/leo/gnu/

Note also that the db.lib and db.a from the EMX distribution
are not suitable for multi-threaded compile (even single-threaded
flavor of Perl uses multi-threaded C RTL, for
compatibility with XFree86-OS/2). Get a corrected one from

http://www.ilyaz.org/software/os2/db_mt.zip

If you have exactly the same version of Perl installed already,
make sure that no copies or perl are currently running. Later steps
of the build may fail since an older version of perl.dll loaded into
memory may be found. Running maketest
becomes meaningless, since
the test are checking a previous build of perl (this situation is detected
and reported by lib/os2_base.t test). Do not forget to unset
PERL_EMXLOAD_SEC
in environment.

Also make sure that you have /tmp directory on the current drive,
and . directory in your LIBPATH
. One may try to correct the
latter condition by

set BEGINLIBPATH .\.

if you use something like CMD.EXE or latest versions of
4os2.exe. (Setting BEGINLIBPATH to just . is ignored by the
OS/2 kernel.)

Make sure your gcc is good for -Zomf
linking: run omflibs
script in /emx/lib directory.

Check that you have link386 installed. It comes standard with OS/2,
but may be not installed due to customization. If typing

link386

shows you do not have it, do Selective install, and choose Linkobjectmodules
in Optional system utilities/More. If you get into
link386 prompts, press Ctrl-C
to exit.

Getting perl source

You need to fetch the latest perl source (including developers
releases). With some probability it is located in

http://www.cpan.org/src/

http://www.cpan.org/src/unsupported

If not, you may need to dig in the indices to find it in the directory
of the current maintainer.

Quick cycle of developers release may break the OS/2 build time to
time, looking into

http://www.cpan.org/ports/os2/

may indicate the latest release which was publicly released by the
maintainer. Note that the release may include some additional patches
to apply to the current source of perl.

Extract it like this

tarvzxfperl5.00409.tar.gz

You may see a message about errors while extracting Configure. This is
because there is a conflict with a similarly-named file configure.

Change to the directory of extraction.

Application of the patches

You need to apply the patches in ./os2/diff.* like this:

gnupatch -p0 < os2\diff.configure

You may also need to apply the patches supplied with the binary
distribution of perl. It also makes sense to look on the
perl5-porters mailing list for the latest OS/2-related patches (see
http://www.xray.mpe.mpg.de/mailing-lists/perl5-porters/). Such
patches usually contain strings /os2/
and patch
, so it makes
sense looking for these strings.

Hand-editing

You may look into the file ./hints/os2.sh and correct anything
wrong you find there. I do not expect it is needed anywhere.

Making

sh Configure -des -D prefix=f:/perllib

prefix
means: where to install the resulting perl library. Giving
correct prefix you may avoid the need to specify PERLLIB_PREFIX
,
see PERLLIB_PREFIX.

Ignore the message about missing ln
, and about -c
option to
tr. The latter is most probably already fixed, if you see it and can trace
where the latter spurious warning comes from, please inform me.

Now

make

At some moment the built may die, reporting a version mismatch or
unable to run perl. This means that you do not have . in
your LIBPATH, so perl.exe cannot find the needed perl67B2.dll (treat
these hex digits as line noise). After this is fixed the build
should finish without a lot of fuss.

Testing

Now run

maketest

All tests should succeed (with some of them skipped). If you have the
same version of Perl installed, it is crucial that you have . early
in your LIBPATH (or in BEGINLIBPATH), otherwise your tests will most
probably test the wrong version of Perl.

Some tests may generate extra messages similar to

A lot of badfree

in database tests related to Berkeley DB. This should be fixed already.
If it persists, you may disable this warnings, see PERL_BADFREE.

Process terminated by SIGTERM/SIGINT

This is a standard message issued by OS/2 applications. *nix
applications die in silence. It is considered to be a feature. One can
easily disable this by appropriate sighandlers.

However the test engine bleeds these message to screen in unexpected
moments. Two messages of this kind should be present during
testing.

Installing the built perl

It would put the generated files into needed locations. Manually put
perl.exe, perl__.exe and perl___.exe to a location on your
PATH, perl.dll to a location on your LIBPATH.

Run

make installcmd INSTALLCMDDIR=d:/ir/on/path

to convert perl utilities to .cmd files and put them on
PATH. You need to put .EXE-utilities on path manually. They are
installed in $prefix/bin
, here $prefix
is what you gave to
Configure, see Making.

If you use man
, either move the installed */man/ directories to
your MANPATH
, or modify MANPATH
to match the location. (One
could have avoided this by providing a correct manpath
option to
./Configure, or editing ./config.sh between configuring and
making steps.)

a.out
-style build

Note. The build process for perl_does not know about all the
dependencies, so you should make sure that anything is up-to-date,
say, by doing

makeperl_dll

first.

Building a binary distribution

[This section provides a short overview only...]

Building should proceed differently depending on whether the version of perl
you install is already present and used on your system, or is a new version
not yet used. The description below assumes that the version is new, so
installing its DLLs and .pm files will not disrupt the operation of your
system even if some intermediate steps are not yet fully working.

The other cases require a little bit more convoluted procedures. Below I
suppose that the current version of Perl is 5.8.2
, so the executables are
named accordingly.

1.

Fully build and test the Perl distribution. Make sure that no tests are
failing with test
and aout_test
targets; fix the bugs in Perl and
the Perl test suite detected by these tests. Make sure that all_test
make target runs as clean as possible. Check that os2/perlrexx.cmd
runs fine.

2.

Fully install Perl, including installcmd
target. Copy the generated DLLs
to LIBPATH
; copy the numbered Perl executables (as in perl5.8.2.exe)
to PATH
; copy perl_.exe
to PATH
as perl_5.8.2.exe
. Think whether
you need backward-compatibility DLLs. In most cases you do not need to install
them yet; but sometime this may simplify the following steps.

3.

Make sure that CPAN.pm
can download files from CPAN. If not, you may need
to manually install Net::FTP
.

This may take a couple of hours on 1GHz processor (when run the first time).
And this should not be necessarily a smooth procedure. Some modules may not
specify required dependencies, so one may need to repeat this procedure several
times until the results stabilize.

Fix as many discovered bugs as possible. Document all the bugs which are not
fixed, and all the failures with unknown reasons. Inspect the produced logs
00cpan_i_1 to find suspiciously skipped tests, and other fishy events.

Keep in mind that installation of some modules may fail too: for example,
the DLLs to update may be already loaded by CPAN.pm. Inspect the install
logs (in the example above 00cpan_i_1 etc) for errors, and install things
manually, as in

cd $CPANHOME/.cpan/build/Digest-MD5-2.31

make install

Some distributions may fail some tests, but you may want to install them
anyway (as above, or via forceinstall
command of CPAN.pm
shell-mode).

Since this procedure may take quite a long time to complete, it makes sense
to "freeze" your CPAN configuration by disabling periodic updates of the
local copy of CPAN index: set index_expire
to some big value (I use 365),
then save the settings

CPAN> o conf index_expire 365

CPAN> o conf commit

Reset back to the default value 1
when you are finished.

5.

When satisfied with the results, rerun the installcmd
target. Now you
can copy perl5.8.2.exe
to perl.exe
, and install the other OMF-build
executables: perl__.exe
etc. They are ready to be used.

6.

Change to the ./pod directory of the build tree, download the Perl logo
CamelGrayBig.BMP, and run

( perl2ipf > perl.ipf ) |& tee 00ipf

ipfc /INF perl.ipf |& tee 00inf

This produces the Perl docs online book perl.INF
. Install in on
BOOKSHELF
path.

7.

Now is the time to build statically linked executable perl_.exe which
includes newly-installed via Bundle::OS2_default
modules. Doing testing
via CPAN.pm
is going to be painfully slow, since it statically links
a new executable per XS extension.

Again, this procedure should not be absolutely smooth. Some Makefile.PL
's
in subdirectories may be buggy, and would not run as "child" scripts. The
interdependency of modules can strike you; however, since non-XS modules
are already installed, the prerequisites of most modules have a very good
chance to be present.

If you discover some glitches, move directories of problematic modules to a
different location; if these modules are non-XS modules, you may just ignore
them - they are already installed; the remaining, XS, modules you need to
install manually one by one.

After each such removal you need to rerun the Makefile.PL
/make
process;
usually this procedure converges soon. (But be sure to convert all the
necessary external C libraries from .lib format to .a format: run one of

emxaoutfoo.lib

emximp -o foo.afoo.lib

whichever is appropriate.) Also, make sure that the DLLs for external
libraries are usable with with executables compiled without -Zmtd
options.

When you are sure that only a few subdirectories
lead to failures, you may want to add -j4
option to make
to speed up
skipping subdirectories with already finished build.

When you are satisfied with the results of tests, install the build C libraries
for extensions:

make install |& tee 00aout_i

Now you can rename the file ./perl.exe generated during the last phase
to perl_5.8.2.exe; place it on PATH
; if there is an inter-dependency
between some XS modules, you may need to repeat the test
/install
loop
with this new executable and some excluded modules - until the procedure
converges.

Now you have all the necessary .a libraries for these Perl modules in the
places where Perl builder can find it. Use the perl builder: change to an
empty directory, create a "dummy" Makefile.PL again, and run

perl_5.8.2.exe Makefile.PL |& tee 00c

make perl |& tee 00p

This should create an executable ./perl.exe with all the statically loaded
extensions built in. Compare the generated perlmain.c files to make sure
that during the iterations the number of loaded extensions only increases.
Rename ./perl.exe to perl_5.8.2.exe on PATH
.

When it converges, you got a functional variant of perl_5.8.2.exe; copy it
to perl_.exe
. You are done with generation of the local Perl installation.

8.

Make sure that the installed modules are actually installed in the location
of the new Perl, and are not inherited from entries of @INC given for
inheritance from the older versions of Perl: set PERLLIB_582_PREFIX
to
redirect the new version of Perl to a new location, and copy the installed
files to this new location. Redo the tests to make sure that the versions of
modules inherited from older versions of Perl are not needed.

Actually, the log output of pod2ipf during the step 6 gives a very detailed
info about which modules are loaded from which place; so you may use it as
an additional verification tool.

Check that some temporary files did not make into the perl install tree.
Run something like this

Compress all the DLLs with lxlite. The tiny .exe can be compressed with
/c:max (the bug only appears when there is a fixup in the last 6 bytes of a
page (?); since the tiny executables are much smaller than a page, the bug
will not hit). Do not compress perl_.exe
- it would not work under DOS.

9.

Now you can generate the binary distribution. This is done by running the
test of the CPAN distribution OS2::SoftInstaller
. Tune up the file
test.pl to suit the layout of current version of Perl first. Do not
forget to pack the necessary external DLLs accordingly. Include the
description of the bugs and test suite failures you could not fix. Include
the small-stack versions of Perl executables from Perl build directory.

Include perl5.def so that people can relink the perl DLL preserving
the binary compatibility, or can create compatibility DLLs. Include the diff
files (diff -puoldnew
) of fixes you did so that people can rebuild your
version. Include perl5.map so that one can use remote debugging.

10.

Share what you did with the other people. Relax. Enjoy fruits of your work.

11.

Brace yourself for thanks, bug reports, hate mail and spam coming as result
of the previous step. No good deed should remain unpunished!

Building custom .EXE files

The Perl executables can be easily rebuilt at any moment. Moreover, one can
use the embedding interface (see perlembed) to make very customized
executables.

Making executables with a custom collection of statically loaded extensions

It is a little bit easier to do so while decreasing the list of statically
loaded extensions. We discuss this case only here.

Run it with the flavor of Perl (perl.exe or perl_.exe) you want to
rebuild.

perl_Makefile.PL

3.

Ask it to create new Perl executable:

makeperl

(you may need to manually add PERLTYPE=-DPERL_CORE
to this commandline on
some versions of Perl; the symptom is that the command-line globbing does not
work from OS/2 shells with the newly-compiled executable; check with

.\perl.exe -wle "print for @ARGV" *

).

4.

The previous step created perlmain.c which contains a list of newXS() calls
near the end. Removing unnecessary calls, and rerunning

makeperl

will produce a customized executable.

Making executables with a custom search-paths

The default perl executable is flexible enough to support most usages.
However, one may want something yet more flexible; for example, one may want
to find Perl DLL relatively to the location of the EXE file; or one may want
to ignore the environment when setting the Perl-library search patch, etc.

If you fill comfortable with embedding interface (see perlembed), such
things are easy to do repeating the steps outlined in Making executables with a custom collection of statically loaded extensions, and
doing more comprehensive edits to main() of perlmain.c. The people with
little desire to understand Perl can just rename main(), and do necessary
modification in a custom main() which calls the renamed function in appropriate
time.

However, there is a third way: perl DLL exports the main() function and several
callbacks to customize the search path. Below is a complete example of a
"Perl loader" which

1.

Looks for Perl DLL in the directory $exedir/../dll;

2.

Prepends the above directory to BEGINLIBPATH
;

3.

Fails if the Perl DLL found via BEGINLIBPATH
is different from what was
loaded on step 1; e.g., another process could have loaded it from LIBPATH
or from a different value of BEGINLIBPATH
. In these cases one needs to
modify the setting of the system so that this other process either does not
run, or loads the DLL from BEGINLIBPATH
with LIBPATHSTRICT=T
(available
with kernels after September 2000).

4.

Loads Perl library from $exedir/../dll/lib/.

5.

Uses Bourne shell from $exedir/../dll/sh/ksh.exe.

For best results compile the C file below with the same options as the Perl
DLL. However, a lot of functionality will work even if the executable is not
an EMX applications, e.g., if compiled with

op/sprintf test failure

Specific (mis)features of OS/2 port

Note that these functions are compatible with *nix, not with the older
ports of '94 - 95. The priorities are absolute, go from 32 to -95,
lower is quicker. 0 is the default priority.

WARNING. Calling getpriority on a non-existing process could lock
the system before Warp3 fixpak22. Starting with Warp3, Perl will use
a workaround: it aborts getpriority() if the process is not present.
This is not possible on older versions 2.*
, and has a race
condition anyway.

Multi-argument form of system() allows an additional numeric
argument. The meaning of this argument is described in
OS2::Process.

When finding a program to run, Perl first asks the OS to look for executables
on PATH
(OS/2 adds extension .exe if no extension is present).
If not found, it looks for a script with possible extensions
added in this order: no extension, .cmd, .btm,
.bat, .pl. If found, Perl checks the start of the file for magic
strings "#!"
and "extproc "
. If found, Perl uses the rest of the
first line as the beginning of the command line to run this script. The
only mangling done to the first line is extraction of arguments (currently
up to 3), and ignoring of the path-part of the "interpreter" name if it can't
be found using the full path.

E.g., system'foo','bar','baz'
may lead Perl to finding
C:/emx/bin/foo.cmd with the first line being

extproc /bin/bash -x -c

If /bin/bash.exe is not found, then Perl looks for an executable bash.exe on
PATH
. If found in C:/emx.add/bin/bash.exe, then the above system() is
translated to

The above search for "interpreter" is recursive: if bash executable is not
found, but bash.btm is found, Perl will investigate its first line etc.
The only hardwired limit on the recursion depth is implicit: there is a limit
4 on the number of additional arguments inserted before the actual arguments
given to system(). In particular, if no additional arguments are specified
on the "magic" first lines, then the limit on the depth is 4.

If Perl finds that the found executable is of PM type when the
current session is not, it will start the new process in a separate session of
necessary type. Call via OS2::Process
to disable this magic.

WARNING. Due to the described logic, you need to explicitly
specify .com extension if needed. Moreover, if the executable
perl5.6.1 is requested, Perl will not look for perl5.6.1.exe.
[This may change in the future.]

extproc
on the first line

If the first chars of a Perl script are "extproc "
, this line is treated
as #!
-line, thus all the switches on this line are processed (twice
if script was started via cmd.exe). See DESCRIPTION in perlrun.

Additional modules:

OS2::Process, OS2::DLL, OS2::REXX, OS2::PrfDB, OS2::ExtAttr. These
modules provide access to additional numeric argument for system
and to the information about the running process,
to DLLs having functions with REXX signature and to the REXX runtime, to
OS/2 databases in the .INI format, and to Extended Attributes.

Two additional extensions by Andreas Kaiser, OS2::UPM
, and
OS2::FTP
, are included into ILYAZ
directory, mirrored on CPAN.
Other OS/2-related extensions are available too.

I know of no way to find out the state of popups before the first call
to this function.

OS2::Errors2Drive(drive)

Returns undef if it was not called yet, otherwise return false if errors
were not requested to be written to a hard drive, or the drive letter if
this was requested.

This function may redirect error popups associated with hardware errors
(Disk not ready etc.) and software exceptions to the file POPUPLOG.OS2 at
the root directory of the specified drive. Overrides OS2::Error() specified
by individual programs. Given argument undef will disable redirection.

Has global effect, persists after the application exits.

I know of no way to find out the state of redirection of popups to the disk
before the first call to this function.

OS2::SysInfo()

Returns a hash with system information. The keys of the hash are

MAX_PATH_LENGTH,MAX_TEXT_SESSIONS,MAX_PM_SESSIONS,

MAX_VDM_SESSIONS,BOOT_DRIVE,DYN_PRI_VARIATION,

MAX_WAIT,MIN_SLICE,MAX_SLICE,PAGE_SIZE,

VERSION_MAJOR,VERSION_MINOR,VERSION_REVISION,

MS_COUNT,TIME_LOW,TIME_HIGH,TOTPHYSMEM,TOTRESMEM,

TOTAVAILMEM,MAXPRMEM,MAXSHMEM,TIMER_INTERVAL,

MAX_COMP_LENGTH,FOREGROUND_FS_SESSION,

FOREGROUND_PROCESS

OS2::BootDrive()

Returns a letter without colon.

OS2::MorphPM(serve)
, OS2::UnMorphPM(serve)

Transforms the current application into a PM application and back.
The argument true means that a real message loop is going to be served.
OS2::MorphPM() returns the PM message queue handle as an integer.

Gives the information about the Perl DLL or the DLL containing the C
function bound to by &xsub
. The meaning of how
is: default (2):
full name; 0: handle; 1: module name.

(Note that some of these may be moved to different libraries -
eventually).

Prebuilt variables:

$OS2::emx_rev

numeric value is the same as _emx_rev of EMX, a string value the same
as _emx_vprt (similar to 0.9c).

$OS2::emx_env

same as _emx_env of EMX, a number similar to 0x8001.

$OS2::os_ver

a number OS_MAJOR + 0.001 * OS_MINOR
.

$OS2::is_aout

true if the Perl library was compiled in AOUT format.

$OS2::can_fork

true if the current executable is an AOUT EMX executable, so Perl can
fork. Do not use this, use the portable check for
$Config::Config{dfork}.

$OS2::nsyserror

This variable (default is 1) controls whether to enforce the contents
of $^E to start with SYS0003
-like id. If set to 0, then the string
value of $^E is what is available from the OS/2 message file. (Some
messages in this file have an SYS0003
-like id prepended, some not.)

Misfeatures

Since flock(3) is present in EMX, but is not functional, it is
emulated by perl. To disable the emulations, set environment variable
USE_PERL_FLOCK=0
.

Here is the list of things which may be "broken" on
EMX (from EMX docs):

The functions recvmsg(3), sendmsg(3), and socketpair(3) are not
implemented.

sock_init(3) is not required and not implemented.

flock(3) is not yet implemented (dummy function). (Perl has a workaround.)

kill(3): Special treatment of PID=0, PID=1 and PID=-1 is not implemented.

Unix-domain sockets on OS/2 live in a pseudo-file-system /sockets/...
.
To avoid a failure to create a socket with a name of a different form,
"/socket/"
is prepended to the socket name (unless it starts with this
already).

This may lead to problems later in case the socket is accessed via the
"usual" file-system calls using the "initial" name.

Apparently, IBM used a compiler (for some period of time around '95?) which
changes FP mask right and left. This is not that bad for IBM's
programs, but the same compiler was used for DLLs which are used with
general-purpose applications. When these DLLs are used, the state of
floating-point flags in the application is not predictable.

What is much worse, some DLLs change the floating point flags when in
_DLLInitTerm() (e.g., TCP32IP). This means that even if you do not call
any function in the DLL, just the act of loading this DLL will reset your
flags. What is worse, the same compiler was used to compile some HOOK DLLs.
Given that HOOK dlls are executed in the context of all the applications
in the system, this means a complete unpredictability of floating point
flags on systems using such HOOK DLLs. E.g., GAMESRVR.DLL of DIVE
origin changes the floating point flags on each write to the TTY of a VIO
(windowed text-mode) applications.

Some other (not completely debugged) situations when FP flags change include
some video drivers (?), and some operations related to creation of the windows.
People who code OpenGL may have more experience on this.

Perl is generally used in the situation when all the floating-point
exceptions are ignored, as is the default under EMX. If they are not ignored,
some benign Perl programs would get a SIGFPE
and would die a horrible death.

To circumvent this, Perl uses two hacks. They help against one type of
damage only: FP flags changed when loading a DLL.

One of the hacks is to disable floating point exceptions on Perl startup (as
is the default with EMX). This helps only with compile-time-linked DLLs
changing the flags before main() had a chance to be called.

The other hack is to restore FP flags after a call to dlopen(). This helps
against similar damage done by DLLs _DLLInitTerm() at runtime. Currently
no way to switch these hacks off is provided.

Since flock(3) is present in EMX, but is not functional, it is
emulated by perl. To disable the emulations, set environment variable
USE_PERL_FLOCK=0
.

Identifying DLLs

All the DLLs built with the current versions of Perl have ID strings
identifying the name of the extension, its version, and the version
of Perl required for this DLL. Run bldlevelDLL-name
to find this
info.

Centralized management of resources

Since to call certain OS/2 API one needs to have a correctly initialized
Win
subsystem, OS/2-specific extensions may require getting HAB
s and
HMQ
s. If an extension would do it on its own, another extension could
fail to initialize.

Perl provides a centralized management of these resources:

HAB

To get the HAB, the extension should call hab = perl_hab_GET()
in C. After
this call is performed, hab
may be accessed as Perl_hab
. There is
no need to release the HAB after it is used.

the extension needs an HMQ
only because some API will not work otherwise.
Use serve = 0
below.

the extension needs an HMQ
since it wants to engage in a PM event loop.
Use serve = 1
below.

To get an HMQ
, the extension should call hmq = perl_hmq_GET(serve)
in C.
After this call is performed, hmq
may be accessed as Perl_hmq
.

To signal to Perl that HMQ is not needed any more, call
perl_hmq_UNSET(serve)
. Perl process will automatically morph/unmorph itself
into/from a PM process if HMQ is needed/not-needed. Perl will automatically
enable/disable WM_QUIT
message during shutdown if the message queue is
served/not-served.

NOTE. If during a shutdown there is a message queue which did not disable
WM_QUIT, and which did not process the received WM_QUIT message, the
shutdown will be automatically cancelled. Do not call perl_hmq_GET(1)
unless you are going to process messages on an orderly basis.

Treating errors reported by OS/2 API

There are two principal conventions (it is useful to call them Dos*
and Win*
- though this part of the function signature is not always
determined by the name of the API) of reporting the error conditions
of OS/2 API. Most of Dos*
APIs report the error code as the result
of the call (so 0 means success, and there are many types of errors).
Most of Win*
API report success/fail via the result being
TRUE
/FALSE
; to find the reason for the failure one should call
WinGetLastError() API.

Some Win*
entry points also overload a "meaningful" return value
with the error indicator; having a 0 return value indicates an error.
Yet some other Win*
entry points overload things even more, and 0
return value may mean a successful call returning a valid value 0, as
well as an error condition; in the case of a 0 return value one should
call WinGetLastError() API to distinguish a successful call from a
failing one.

By convention, all the calls to OS/2 API should indicate their
failures by resetting $^E. All the Perl-accessible functions which
call OS/2 API may be broken into two classes: some die()s when an API
error is encountered, the other report the error via a false return
value (of course, this does not concern Perl-accessible functions
which expect a failure of the OS/2 API call, having some workarounds
coded).

Obviously, in the situation of the last type of the signature of an OS/2
API, it is must more convenient for the users if the failure is
indicated by die()ing: one does not need to check $^E to know that
something went wrong. If, however, this solution is not desirable by
some reason, the code in question should reset $^E to 0 before making
this OS/2 API call, so that the caller of this Perl-accessible
function has a chance to distinguish a success-but-0-return value from
a failure. (One may return undef as an alternative way of reporting
an error.)

Returns expr
, sets $^E from WinGetLastError() if expr
is false,
and die()s if die and $^E are true. The message to die is the
concatenated strings name1
and name2
, separated by ": "
from
the contents of $^E.

WinError_2_Perl_rc

Sets Perl_rc
to the return value of WinGetLastError().

FillWinError

Sets Perl_rc
to the return value of WinGetLastError(), and sets $^E
to the corresponding value.

FillOSError(rc)

Sets Perl_rc
to rc
, and sets $^E to the corresponding value.

Loading DLLs and ordinals in DLLs

Some DLLs are only present in some versions of OS/2, or in some
configurations of OS/2. Some exported entry points are present only
in DLLs shipped with some versions of OS/2. If these DLLs and entry
points were linked directly for a Perl executable/DLL or from a Perl
extensions, this binary would work only with the specified
versions/setups. Even if these entry points were not needed, the
load of the executable (or DLL) would fail.

For example, many newer useful APIs are not present in OS/2 v2; many
PM-related APIs require DLLs not available on floppy-boot setup.

To make these calls fail only when the calls are executed, one
should call these API via a dynamic linking API. There is a subsystem
in Perl to simplify such type of calls. A large number of entry
points available for such linking is provided (see entries_ordinals
- and also PMWIN_entries
- in os2ish.h). These ordinals can be
accessed via the APIs:

CallORD(),DeclFuncByORD(),DeclVoidFuncByORD(),

DeclOSFuncByORD(),DeclWinFuncByORD(),AssignFuncPByORD(),

DeclWinFuncByORD_CACHE(),DeclWinFuncByORD_CACHE_survive(),

DeclWinFuncByORD_CACHE_resetError_survive(),

DeclWinFunc_CACHE(),DeclWinFunc_CACHE_resetError(),

DeclWinFunc_CACHE_survive(),DeclWinFunc_CACHE_resetError_survive()

See the header files and the C code in the supplied OS/2-related
modules for the details on usage of these functions.

Some of these functions also combine dynaloading semantic with the
error-propagation semantic discussed above.

Perl flavors

Because of idiosyncrasies of OS/2 one cannot have all the eggs in the
same basket (though EMX environment tries hard to overcome this
limitations, so the situation may somehow improve). There are 4
executables for Perl provided by the distribution:

perl.exe

The main workhorse. This is a chimera executable: it is compiled as an
a.out
-style executable, but is linked with omf
-style dynamic
library perl.dll, and with dynamic CRT DLL. This executable is a
VIO application.

It can load perl dynamic extensions, and it can fork().

Note. Keep in mind that fork() is needed to open a pipe to yourself.

perl_.exe

This is a statically linked a.out
-style executable. It cannot
load dynamic Perl extensions. The executable supplied in binary
distributions has a lot of extensions prebuilt, thus the above restriction is
important only if you use custom-built extensions. This executable is a VIO
application.

This is the only executable with does not require OS/2. The
friends locked into M$
world would appreciate the fact that this
executable runs under DOS, Win0.3*, Win0.95 and WinNT with an
appropriate extender. See Other OSes.

perl__.exe

This is the same executable as perl___.exe, but it is a PM
application.

Note. Usually (unless explicitly redirected during the startup)
STDIN, STDERR, and STDOUT of a PM
application are redirected to nul. However, it is possible to see
them if you start perl__.exe
from a PM program which emulates a
console window, like Shell mode of Emacs or EPM. Thus it is
possible to use Perl debugger (see perldebug) to debug your PM
application (but beware of the message loop lockups - this will not
work if you have a message queue to serve, unless you hook the serving
into the getc() function of the debugger).

Another way to see the output of a PM program is to run it as

pm_progargs2>&1 | cat -

with a shell different from cmd.exe, so that it does not create
a link between a VIO session and the session of pm_porg
. (Such a link
closes the VIO window.) E.g., this works with sh.exe - or with Perl!

The flavor perl__.exe is required if you want to start your program without
a VIO window present, but not detach
ed (run helpdetach
for more info).
Very useful for extensions which use PM, like Perl/Tk
or OpenGL
.

Note also that the differences between PM and VIO executables are only
in the default behaviour. One can start any executable in
any kind of session by using the arguments /fs, /pm or
/win switches of the command start
(of CMD.EXE or a similar
shell). Alternatively, one can use the numeric first argument of the
system Perl function (see OS2::Process).

perl___.exe

This is an omf
-style executable which is dynamically linked to
perl.dll and CRT DLL. I know no advantages of this executable
over perl.exe
, but it cannot fork() at all. Well, one advantage is
that the build process is not so convoluted as with perl.exe
.

Why dynamic linking?

Well, having several executables dynamically linked to the same huge
library has its advantages, but this would not substantiate the
additional work to make it compile. The reason is the complicated-to-developers
but very quick and convenient-to-users "hard" dynamic linking used by OS/2.

There are two distinctive features of the dyna-linking model of OS/2:
first, all the references to external functions are resolved at the compile time;
second, there is no runtime fixup of the DLLs after they are loaded into memory.
The first feature is an enormous advantage over other models: it avoids
conflicts when several DLLs used by an application export entries with
the same name. In such cases "other" models of dyna-linking just choose
between these two entry points using some random criterion - with predictable
disasters as results. But it is the second feature which requires the build
of perl.dll.

The address tables of DLLs are patched only once, when they are
loaded. The addresses of the entry points into DLLs are guaranteed to be
the same for all the programs which use the same DLL. This removes the
runtime fixup - once DLL is loaded, its code is read-only.

While this allows some (significant?) performance advantages, this makes life
much harder for developers, since the above scheme makes it impossible
for a DLL to be "linked" to a symbol in the .EXE file. Indeed, this
would need a DLL to have different relocations tables for the
(different) executables which use this DLL.

However, a dynamically loaded Perl extension is forced to use some symbols
from the perl
executable, e.g., to know how to find the arguments to the functions:
the arguments live on the perl
internal evaluation stack. The solution is to put the main code of
the interpreter into a DLL, and make the .EXE file which just loads
this DLL into memory and supplies command-arguments. The extension DLL
cannot link to symbols in .EXE, but it has no problem linking
to symbols in the .DLL.

This greatly increases the load time for the application (as well as
complexity of the compilation). Since interpreter is in a DLL,
the C RTL is basically forced to reside in a DLL as well (otherwise
extensions would not be able to use CRT). There are some advantages if
you use different flavors of perl, such as running perl.exe and
perl__.exe simultaneously: they share the memory of perl.dll.

NOTE. There is one additional effect which makes DLLs more wasteful:
DLLs are loaded in the shared memory region, which is a scarse resource
given the 512M barrier of the "standard" OS/2 virtual memory. The code of
.EXE files is also shared by all the processes which use the particular
.EXE, but they are "shared in the private address space of the process";
this is possible because the address at which different sections
of the .EXE file are loaded is decided at compile-time, thus all the
processes have these sections loaded at same addresses, and no fixup
of internal links inside the .EXE is needed.

Since DLLs may be loaded at run time, to have the same mechanism for DLLs
one needs to have the address range of any of the loaded DLLs in the
system to be available in all the processes which did not load a particular
DLL yet. This is why the DLLs are mapped to the shared memory region.

Why chimera build?

Current EMX environment does not allow DLLs compiled using Unixish
a.out
format to export symbols for data (or at least some types of
data). This forces omf
-style compile of perl.dll.

Current EMX environment does not allow .EXE files compiled in
omf
format to fork(). fork() is needed for exactly three Perl
operations:

While these operations are not questions of life and death, they are
needed for a lot of
useful scripts. This forces a.out
-style compile of
perl.exe.

ENVIRONMENT

Here we list environment variables with are either OS/2- and DOS- and
Win*-specific, or are more important under OS/2 than under other OSes.

PERLLIB_PREFIX

Specific for EMX port. Should have the form

path1;path2

or

path1path2

If the beginning of some prebuilt path matches path1, it is
substituted with path2.

Should be used if the perl library is moved from the default
location in preference to PERL(5)LIB, since this would not leave wrong
entries in @INC. For example, if the compiled version of perl looks for @INC
in f:/perllib/lib, and you want to install the library in
h:/opt/gnu, do

set PERLLIB_PREFIX=f:/perllib/lib;h:/opt/gnu

This will cause Perl with the prebuilt @INC of

f:/perllib/lib/5.00553/os2

f:/perllib/lib/5.00553

f:/perllib/lib/site_perl/5.00553/os2

f:/perllib/lib/site_perl/5.00553

.

to use the following @INC:

h:/opt/gnu/5.00553/os2

h:/opt/gnu/5.00553

h:/opt/gnu/site_perl/5.00553/os2

h:/opt/gnu/site_perl/5.00553

.

PERL_BADLANG

If 0, perl ignores setlocale() failing. May be useful with some
strange locales.

PERL_BADFREE

If 0, perl would not warn of in case of unwarranted free(). With older
perls this might be
useful in conjunction with the module DB_File, which was buggy when
dynamically linked and OMF-built.

Should not be set with newer Perls, since this may hide some real problems.

PERL_SH_DIR

Specific for EMX port. Gives the directory part of the location for
sh.exe.

USE_PERL_FLOCK

Specific for EMX port. Since flock(3) is present in EMX, but is not
functional, it is emulated by perl. To disable the emulations, set
environment variable USE_PERL_FLOCK=0
.

TMP
or TEMP

Specific for EMX port. Used as storage place for temporary files.

Evolution

Here we list major changes which could make you by surprise.

Text-mode filehandles

Starting from version 5.8, Perl uses a builtin translation layer for
text-mode files. This replaces the efficient well-tested EMX layer by
some code which should be best characterized as a "quick hack".

In addition to possible bugs and an inability to follow changes to the
translation policy with off/on switches of TERMIO translation, this
introduces a serious incompatible change: before sysread() on
text-mode filehandles would go through the translation layer, now it
would not.

Priorities

setpriority and getpriority are not compatible with earlier
ports by Andreas Kaiser. See "setpriority, getpriority"
.

DLL name mangling: pre 5.6.2

With the release 5.003_01 the dynamically loadable libraries
should be rebuilt when a different version of Perl is compiled. In particular,
DLLs (including perl.dll) are now created with the names
which contain a checksum, thus allowing workaround for OS/2 scheme of
caching DLLs.

It may be possible to code a simple workaround which would

find the old DLLs looking through the old @INC;

mangle the names according to the scheme of new perl and copy the DLLs to
these names;

edit the internal LX
tables of DLL to reflect the change of the name
(probably not needed for Perl extension DLLs, since the internally coded names
are not used for "specific" DLLs, they used only for "global" DLLs).

edit the internal IMPORT
tables and change the name of the "old"
perl????.dll to the "new" perl????.dll.

DLL name mangling: 5.6.2 and beyond

In fact mangling of extension DLLs was done due to misunderstanding
of the OS/2 dynaloading model. OS/2 (effectively) maintains two
different tables of loaded DLL:

Global DLLs

those loaded by the base name from LIBPATH
; including those
associated at link time;

specific DLLs

loaded by the full name.

When resolving a request for a global DLL, the table of already-loaded
specific DLLs is (effectively) ignored; moreover, specific DLLs are
always loaded from the prescribed path.

There is/was a minor twist which makes this scheme fragile: what to do
with DLLs loaded from

BEGINLIBPATH
and ENDLIBPATH

(which depend on the process)

. from LIBPATH

which effectively depends on the process (although LIBPATH
is the
same for all the processes).

Unless LIBPATHSTRICT
is set to T
(and the kernel is after
2000/09/01), such DLLs are considered to be global. When loading a
global DLL it is first looked in the table of already-loaded global
DLLs. Because of this the fact that one executable loaded a DLL from
BEGINLIBPATH
and ENDLIBPATH
, or . from LIBPATH
may affect
which DLL is loaded when another executable requests a DLL with
the same name. This is the reason for version-specific mangling of
the DLL name for perl DLL.

Since the Perl extension DLLs are always loaded with the full path,
there is no need to mangle their names in a version-specific ways:
their directory already reflects the corresponding version of perl,
and @INC takes into account binary compatibility with older version.
Starting from 5.6.2
the name mangling scheme is fixed to be the
same as for Perl 5.005_53 (same as in a popular binary release). Thus
new Perls will be able to resolve the names of old extension DLLs
if @INC allows finding their directories.

However, this still does not guarantee that these DLL may be loaded.
The reason is the mangling of the name of the Perl DLL. And since
the extension DLLs link with the Perl DLL, extension DLLs for older
versions would load an older Perl DLL, and would most probably
segfault (since the data in this DLL is not properly initialized).

There is a partial workaround (which can be made complete with newer
OS/2 kernels): create a forwarder DLL with the same name as the DLL of
the older version of Perl, which forwards the entry points to the
newer Perl's DLL. Make this DLL accessible on (say) the BEGINLIBPATH
of
the new Perl executable. When the new executable accesses old Perl's
extension DLLs, they would request the old Perl's DLL by name, get the
forwarder instead, so effectively will link with the currently running
(new) Perl DLL.

This may break in two ways:

Old perl executable is started when a new executable is running has
loaded an extension compiled for the old executable (ouph!). In this
case the old executable will get a forwarder DLL instead of the old
perl DLL, so would link with the new perl DLL. While not directly
fatal, it will behave the same as new executable. This beats the whole
purpose of explicitly starting an old executable.

A new executable loads an extension compiled for the old executable
when an old perl executable is running. In this case the extension
will not pick up the forwarder - with fatal results.

With support for LIBPATHSTRICT
this may be circumvented - unless
one of DLLs is started from . from LIBPATH
(I do not know
whether LIBPATHSTRICT
affects this case).

REMARK. Unless newer kernels allow . in BEGINLIBPATH
(older
do not), this mess cannot be completely cleaned. (It turns out that
as of the beginning of 2002, . is not allowed, but .\. is - and
it has the same effect.)

REMARK. LIBPATHSTRICT
, BEGINLIBPATH
and ENDLIBPATH
are
not environment variables, although cmd.exe emulates them on SET
...
lines. From Perl they may be accessed by Cwd::extLibpath and
Cwd::extLibpath_set.

DLL forwarder generation

Assume that the old DLL is named perlE0AC.dll (as is one for
5.005_53), and the new version is 5.6.1. Create a file
perl5shim.def-leader with

in the Perl build directory (to make the DLL smaller replace perl5.def
with the definition file for the older version of Perl if present).

catperl5shim.def-leaderlst >perl5shim.def

gcc -Zomf -Zdll -o perlE0AC.dllperl5shim.def -s -llibperl

(ignore multiple warningL4085
).

Threading

As of release 5.003_01 perl is linked to multithreaded C RTL
DLL. If perl itself is not compiled multithread-enabled, so will not be perl's
malloc(). However, extensions may use multiple thread on their own
risk.

This was needed to compile Perl/Tk
for XFree86-OS/2 out-of-the-box, and
link with DLLs for other useful libraries, which typically are compiled
with -Zmt -Zcrtdll
.

Calls to external programs

Due to a popular demand the perl external program calling has been
changed wrt Andreas Kaiser's port. If perl needs to call an
external program via shell, the f:/bin/sh.exe will be called, or
whatever is the override, see PERL_SH_DIR.

Thus means that you need to get some copy of a sh.exe as well (I
use one from pdksh). The path F:/bin above is set up automatically during
the build to a correct value on the builder machine, but is
overridable at runtime,

Reasons: a consensus on perl5-porters
was that perl should use
one non-overridable shell per platform. The obvious choices for OS/2
are cmd.exe and sh.exe. Having perl build itself would be impossible
with cmd.exe as a shell, thus I picked up sh.exe
. This assures almost
100% compatibility with the scripts coming from *nix. As an added benefit
this works as well under DOS if you use DOS-enabled port of pdksh
(see Prerequisites).

Disadvantages: currently sh.exe of pdksh calls external programs
via fork()/exec(), and there is no functioning exec() on
OS/2. exec() is emulated by EMX by an asynchronous call while the caller
waits for child completion (to pretend that the pid
did not change). This
means that 1 extra copy of sh.exe is made active via fork()/exec(),
which may lead to some resources taken from the system (even if we do
not count extra work needed for fork()ing).

Note that this a lesser issue now when we do not spawn sh.exe
unless needed (metachars found).

which will override system(), exec(), ``
, and
open(,'...|'). With current perl you may override only system(),
readpipe() - the explicit version of ``
, and maybe exec(). The code
will substitute the one-argument call to system() by
CORE::system('cmd.exe','/c',shift)
.

If you have some working code for OS2::Cmd
, please send it to me,
I will include it into distribution. I have no need for such a module, so
cannot test it.

External scripts may be called by their basename. Perl will try the same
extensions as when processing -S command-line switch.

External scripts starting with #!
or extproc
will be executed directly,
without calling the shell, by calling the program specified on the rest of
the first line.

Memory allocation

Perl uses its own malloc() under OS/2 - interpreters are usually malloc-bound
for speed, but perl is not, since its malloc is lightning-fast.
Perl-memory-usage-tuned benchmarks show that Perl's malloc is 5 times quicker
than EMX one. I do not have convincing data about memory footprint, but
a (pretty random) benchmark showed that Perl's one is 5% better.

Combination of perl's malloc() and rigid DLL name resolution creates
a special problem with library functions which expect their return value to
be free()d by system's free(). To facilitate extensions which need to call
such functions, system memory-allocation functions are still available with
the prefix emx_
added. (Currently only DLL perl has this, it should
propagate to perl_.exe shortly.)

Threads

One can build perl with thread support enabled by providing -Dusethreads
option to Configure. Currently OS/2 support of threads is very
preliminary.

Most notable problems:

COND_WAIT

may have a race condition (but probably does not due to edge-triggered
nature of OS/2 Event semaphores). (Needs a reimplementation (in terms of chaining
waiting threads, with the linked list stored in per-thread structure?)?)

os2.c

has a couple of static variables used in OS/2-specific functions. (Need to be
moved to per-thread structure, or serialized?)

Note that these problems should not discourage experimenting, since they
have a low probability of affecting small programs.

BUGS

This description is not updated often (since 5.6.1?), see ./os2/Changes
(perlos2delta) for more info.